OREANDA-NEWS. Mobile TeleSystems OJSC (“MTS” - NYSE: MBT), the leading telecommunications operator in Russia and the CIS, announces that Moody`s Investor Service has upgraded MTS's senior unsecured issuer rating from Ba2 to Baa3 with a stable outlook. This represents a two-notch upgrade and classifies MTS as investment grade.

Mobile TeleSystems OJSC ("MTS") is the leading telecommunications group in Russia and the CIS, offering mobile and fixed voice, broadband, pay TV as well as content and entertainment services in one of the world's fastest growing regions. Including its subsidiaries, the Group services over 100 million mobile subscribers. The Group has been awarded GSM licenses in Russia, Ukraine, Turkmenistan, Armenia and Belarus, a region that boasts a total population of more than 200 million. Since June 2000, MTS' Level 3 ADRs have been listed on the New York Stock Exchange (ticker symbol MBT). Additional information about the MTS Group can be found at www.mtsgsm.com <http://www.mtsgsm.com>.